I thought his frames were a 3" layer over a 4" layer over a 6" layer at 3 and 9....

I think, but not 100% sure, that you both are right. I think kiteboard is reffering to the total amount of strips of lead at 3 and 9. 3x4 sides would be 12 strips of lead, and the length could be what you have said. Not 100% sure though

The specs at Gregg Raven's HD Tennis site for Sampras are 384 g, 32.1 cm, and 367 kg•cm^2. Assuming those are strung specs, that would give a polarization index (recoil weight divided by mass) of 0.467, which isn't remarkable either way for stock racquets (the average for the 1200+ racquets on the spreadsheet in front of me is 0.464) and is less polarized than almost all of the pro specs I've run across (the average for 17 ATP players at the 2009 BNP Paribas Open was 0.52).

If you use the specs from the 1993 ATP World Championship in Frankfurt (don't remember where I got them, but they are 390 g, 32.3 cm, 379 kg•cm^2), it comes to 0.475.

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Well IIRC he didn't really mess with his balance and weight distribution, as he wanted it as close to his old Kramer as possible (correct?)

So it could be that those Greg Raven specs are indeed unstrung, as the 379 SW seems more likely considering how much lead he placed at 3 and 9. I myself tried the same amt of lead on my BLX90, and it felt more like 375+ than 367 (similar to how I had my Radical set up at the time)

Well IIRC he didn't really mess with his balance and weight distribution, as he wanted it as close to his old Kramer as possible (correct?)

So it could be that those Greg Raven specs are indeed unstrung, as the 379 SW seems more likely considering how much lead he placed at 3 and 9. I myself tried the same amt of lead on my BLX90, and it felt more like 375+ than 367 (similar to how I had my Radical set up at the time)

I had an old official Babolat RDC list (from 1996) where people like Sampras and others (double liners) were in and i remember that Pete's racket was 388 grams strung.